Combined wireless sending and receiving system



Sept. 15, 1925.

1,553,391 A. NYMAN COMBINED WIRELESS SENDING AND RECEIVING SYSTEM Filed July 15. 1920 WITNESSES: 4 fi/ INVjNTji/Q exam er man.

. Patented Sept. 15, 1925.

ALEXANDER-NYMAN, or wnxmsnune, rENNsYLvANm,

v HOUSE ELECTRIC 86 MANUFACTURING GOMIANY, K COBPORATIOHDF PENNSYL- VANIA.

conenmn wnmr-Es's SENDING AND RECEIVING sxs'rmr;

Application filed iui 15, 1920. Serial o. 896,588.

To all'whom it may concern: Be it known that l, ALEXANDER NYMAN, a citizen of the'United States, and a resident of Wilkinsburg, in the county of Allegheny 6 and State of Pennsylvania, have invented a new and useful Improvement in Combined Wireless Sending and Receiving Systems, of which the following is a specificatlon.

My invention relates to systems for 10 simultaneously sending and receiving messages on the sameapparatus so that the same antenna may be used to both? send and receive without necessitating switching. More particularly, my invention relates to an apparatus for simultaneously sending and receiving radio messages, and to the use of a main'antenna circuit'having inductance, and a shunt circuit having inductance, the inductance of the main and shunt circuits neutralizing each other in their effect upon the receiving circuit when a message is sent -but permitting received oscillations to be caught. .7 It has been difiicult to both send and receiveat-the same time, where communications were being transmitted-and received from. the same station, for the reason that the waves sent from the home station are tuned to the length of those received and the receiving, apparatus responded to both.

It has not been possible to successfully send and receive simultaneously under the above outlined conditions.

This invention is conceived with the idea of rendering feasible the simultaneous use of a wireless apparatus both as a sending and as a receiving station, and, at the same time, to accomplish that result while using the same antenna. v

' An object of myinvention is to provide means for sending and. receiving wireless messages without necessitating any switching operations.

With

V hese and other objects in view, which may be lllcldellt to the improvements, my invention consists 1n the parts and combinations to be hereinafter set forth and claimed, with the understanding that the several elements com rising my invention i arrangement without departing from the spirit and scope of the appended claims.

In order to make my invention more may be varied 'in t eir proportions and clearly understood," I have shown, in the acv companyingv drawings, means for carrying 1t into practical eifect without limiting the improvements, in their useful applications,

to the particular constructions, which, forthe purpose of explanation, have been made the subject of illustration.

is a diagrammatic viewvof a combination AssreNon. mo wEs'rmer In the accompanying drawings, Figure 1f" sending and receiving station constructed in I accordance with the principles of my invention. I

Fig. 2 is-a diagrammatic view'in which the dotted lines indicate the portion of my apparatus which acts as an operative part of the receiving station. Fig. 3' is a diagrammatic view illustrat-v ing the flow of currents in the apparatus when it is used as a sending station. 7 v Fig. 4 is a diagram illustrating the flow oficurrents through my apparatus when it is used as a receiving'station.

Figs. 5 and 6 are diagrams illustrating different arrangements of apparatus that may be used within the spirit of my invention. 7

Referring to the drawings, I have shown an antenna 1 having a neutralizing inductance 2, a main inductance 3 of a variable quantity and a "variable capacitance 4 through which the circuits are grounded. A shunt circuit -is',provided having a variable inductance 5, a variable capacitance 6 and a variable resistance 7.. 'The shunt circuit above mentioned is tuned to approximately the same frequency as 'themain antenna circuit so that oscillations sent or received will pass through the shunt circuit. I have iound, however, that it is not necessary to tune the shunt circuit exactly to the main-antenna-circuit frequency. The variable resistance 7 is adjusted to limit the through the shunt circuit.

In inductive relation to the inductance 3 of the main circuit;is a variable inductance 8 through which power is delivered to the antenna circuit. The variable inductance 8 has a variable capacitance 9 connectedin parallel with it so that the circuit may be circuit through the inductance. 8 and the capacitance 9 is a filament element-10 and .95 7 amount of wasted sending power expended readily tuned to any desired "frequency. In 7 the tube 17 to absorb having a high-reactance a plate element 11 of an electron tube 10 having a grid element l3connected to, the inductance 8 to furnish the feed back between the grid and plate circuits necessary for. sustained oscillations.

A suitable battery 14 provides current for heating the filament element 10. The arrangement is the customary one for using an electron tube as a generator of.radioequency alternating current. In circuit with the plate circuit of the electron tube 10' is a plate 15 and a filament 16 of an electron tube 17, acting as a modulator and having a id element 18. The filament 16 is heated y means of a suitable battery 19.. I

Within the plate circuit of modulator tube 17 is an inductance 20. A G battery 22' is provided in circuit with the grid 18, the negative terminal of which applies its potential to the grid 18. Within the grid circuit is located an inductance 22.

Provided within the circuit of the two eletcron tubes 10' and 17 is a generator 21' coil 22" that acts as a constant source of current and delivers power to the generator tube 10. Coupled inductively to the inductance 22 is an inductance 23 of a microphone circuit that includes a battery 24 and a microphone 25. Variations of the microphone-circuit current by reason of the voice causes a variation in otential of the rid 18 of the modulator tu 17 because 0 the inductive coupling of the inductances 22 and 23 and thus, variation of potential of the grid 16 causes 7 power in accordance with the change of potential.

Though I have shown a generator tube coupled with a modulator as a generator of radio-frequency oscillations the amplitude of which is controlled by voice, any method of (generating sending oscillations maybe use such as the Poulsen arc or the frequency generator, and it is to be understood that my invention is not limited to any particular type of apparatus for generating radio-frequency current but that the apparatus which I have shown is merely highor purposes of illustration.

In inductive relation to the neutralizing inductance 2 of the main antenna circuit and, likewise, to the inductance 5 of the shunt circuit, is an inductance 26 of the receiving circuit. This inductance is so placed that, upon the sending of a message, the inductive efiect of neutralizing inductance 2 and inductance 5 of the shunt circuit will balance and react to produce a zero electromotive force within this coil. This phenomenon will be more fully explained in the paragraphs to follow.

I In circuit with the inductance 26 is a variable capacity 27 and a condenser 28. An elctron tube 29, acting as a detector and having a id element 30, a plate element 31 and a ament element 32, is in circuit with theinductance 26. s

In circuit across the condensers27 and 28 is a resistance33 that performs the func-' tion of the customary grid leak in the grid circuitof tubes acting as detectors.

To heat the filament 32, I provide an .A battery 34. The amount of current flowing through the filament 32 is controlled by the insertion of a variable resistance 34!. Within the plate circuit of the electron tube 29 are located telephone receivers, 35, having a capacity 36 shunted between them. A suitable B'battery 37 applies positive potential to the plate 31. There should be no mutual inductance, as will be apparent, between certainf'of: the coils. To avoid this mutual inductance, these coils may be placed at right angles to each other. To avoid the effect of stray field upon the coils, they may be encased within metalcontainers or boxes. It is most necessary to the eificient operation of this system that the inductance be free from the effect of stray fields and that certain ofthe coils should not have mutual inductance between them, and any methods may be used to obtain these results, the above outlined methods being but two of many that may be employed.

Referring to Fig. 2, which is a diagrammatic illustration of the antenna circuits. the dotted lines surrounding a portion of the circuit indicate the effectivepart of the circuit when the apparatus is used as a receiving circuit. It will be noted that this effective receiving circuit includes the inductance 26, the neutralizing inductance 2 and the inductance 5 of the shunt circuit.

Fig. 3 denotes the direction of the currents in the main and shunt circuits of the antenna when a message is being sent. Since the shunt circuit mate frequencyof the main circuit and is parallel thereto, the flow-0f current in the two circuits is in opposite directions.

By reason of the fact that the neutralizing is tuned to the approxiinductance 2 is a portion of the main antenna circuit, the flow of current in it is in a direction opposite to the flow of current in the inductance 5 of the shunt circuit.

By proper arrangement of the values and positions of these inductances, the effect upon the inductance 26 of the receiving circuit can be made zero since the currents are opposite in phase.

In operatlon of the apparatus as a sending station, the tube 10' is arranged to act as a generator of radio-frequency current, there being mutual inductance between the plate and grid circuits.

The capacity 9 is variable and, likewise, the inductance 8 may be made of variable quantity, so that the sent oscillations may be tuned to the desired frequency,

The tube 17 acts as a modulator of the radio frequency current generated by the tube The microphone 25 causes, oscillations of audio frequency in inductance 23 and this, in turn, induces oscillations'of audio frequency in inductance 22. v

Because of the change in grid pot'ential of Y the grid 18, audio frequency oscillations are set up within the plate circuit of the modulator-tube 17.

In accordance with the well known principles of radio transmission, the audio-frequency oscillations absorb power from the input of the antenna and these audio-frequency oscillations will aifect the amplitude of the radio frequency oscillations sent out.

This produces the audio pulses necessary for.

the transmission of a message.

Fig. 4 illustrates, diagrammatically, the

' flow of currents in the antenna circuit when the apparatus is receiving messages. The currents through the. neutralizing inductance 2 of the main-antenna circuit and through the inductance 5 of the shunt circuit travel in the same direction, and'theefiect upon the inductance 26 of the receiving circuit is the arithmetical sum of the effects of the first mentioned inductances. Thus, oscillations are induced in the inductance 26. This in-' duced current affects the potential of the grid 30, of the electron tube 29 and, as the proper conditions for use of this: tube as a detector are present, oscillations are setup in the plate circuit corresponding to the received oscillations, and messages may be .takenthrough the telephone receivers 35.

By virtue of adjustment of the variable capacity 27, the circuit may betuned to any desired 'freguenc j 'It is obvious that any method of etectlng the received oscillations may beemployed, and that I have shown. an electron tube, usedas a detector of radio frequency, solely for the purpose of illustra- 'tion and to make clear the utility of my in vention and its application to the problems 7 of radio communication.

From the foregoing-it will be apparent that, in the operation of receivmg by reason of the direction of flow of current, the ef-:

-' iect of the neutralizing inductance and the shunt circuit inductance up'on the receiving inductance is the arithmetical sum of these two. However, in sending messages, since the currents'traverse the neutralizing inductance2 and the shunt'circuit inductance 5 in opposite directions, the effect of each tends to neutralize the other in its action upon the receiving inductance, and, by proper adjustment of position of coils and of values, the inductive effect upon the receiving inductance may be made equal to zero when the ap aratus is used as a sending station.

Fig. 5 is shown amo'diiication of the arrangement of circuits that may be em- Fig. 6, in.

inductance 40, that forms part of the antenna circuit.. The operation of the modifications shown in Figs. 5 and 6'is similar to that previously described relative'to the type shown in Figs. 1 to 4, inclusive; in sending, the shunt-circuit inductance and neutralizing inductance balance in their efiects on the receiving inductance while, in receiving,

their effects are added.

While I have described but three embodiments of my. invention, it will be apparent to those skilled in the art that many modifications may be made. therein without departiv ing from the spirit of'the invention and I desire, therefore, that my invention shallbe limited only as set forth in the appended claims or by the showing of the prior art;

I claim as my invention:

1. The combination with a source of cur- V rents having an alternating-current component, of a' translating device adapted to both supply and utilize currents having an alternating-current component, a main neutralizing reactance device, a main circuit ineluding said source, sald mam neutrahzmg reactance device and said translating device, an auxiliary neutralizing reactance device, an energy-absorbing device, an auxiliary circuit including saidfsource, said: main and Y auxiliary neutralizing devices and said .ener circuit coupledto both of said neutralizing devices.

2. The combination with a source of modulated radio-frequency currents, of, a translating device adapted to both-transmit and receive modulated radio-frequency cur,- rents, a main neutralizing reactance device,

a tuned main circuit including said source,

said main neutralizing reactance device and -absorbing device, and a receiving,

said translating device, an auxiliary neutralizing reactance device, an energy-absorbing device, a similarly tuned auxiliary cir-' cuit including said source, said main and auxiliary neutralizing devices and said ener -absorbing device, and a receiving-circult coupled to both of said neutralizing devlces. 3. The combination with a of modulated radio-frequency currents, of an antenna, a main neutr circuit including said source, said main ing device, a tuned neutralizing device and said antenna, an auxiliary neutralizing device comprising an energy absorbent means, an auxiliary circuit including said source, said main and auxiliary neutralizing devices and said energy-absorbing device, and a receiving cir cuit coupled to both ,of'said neutralizing devices.

relation with said inductors, one of the branches of the antenna circuit including an additional inductor adapted to be coupled to asending apparatus, the portion of the other of said branches of the antenna circuit external to the inductor therein being substantially free from inductance, and. means associated with said additional induc- ALEXANDER NYMAN. 

